If your phone is connected to Internet, you can request a backup pin in case it's locked. Either way, the backup pin can be changed from the Security menu in the Settings. It doesn't matter if you use a pattern lock or any other lock, the phone will always ask you to set up a backup pin in case you forgot how to unlock it. So, to request a backup pin at the lock screen, make sure you are connected to Internet then enter the pattern multiple times or random pins and you will then have the possibility to request one to the email account attached to phone.
